Monday, 28 February 2011

When an infant starts walking, this important achievement is more than just a milestone in motor control. According to Melissa Clearfield, the child's newfound locomotor skill arrives hand-in-hand with a raft of other changes in social behaviour and maturity. This is an unfolding, interactive process of development that before now has been little explored by psychologists.

Clearfield first had 17 non-walking infants (aged between 9 and 11 months) twice spend ten minutes exploring a 3m by 3m floor area dotted with toys, and with their mother and three other people positioned in each corner. The infants first explored the area crawling and then in a baby walker (this piece of equipment allows infants who can't yet walk to move around in an upright position as if walking).

The infants spent the same amount of time interacting with toys and people, gesturing and vocalising, whether they were crawling or in the baby walker. In other words, there wasn't anything about being in an upright position per se that changed the social behaviour of these children.

Next, Clearfield had a new group of 16 infants (also aged nine to eleven months) perform the same task, except these children were all walkers. These walking infants, even though they were age-matched to the first group, spent considerably more time vocalising and making socially-directed gestures, such as pointing at or waving a toy whilst looking at their mothers. Overall, the walkers spent three times as much time interacting with their mothers, and twice as much time interacting with the toys, compared with crawlers of the same age.

A final study tested another set of fourteen 9-month-old infants on the same exploratory task, once a month for six months, to see how their behaviour changed, not by virtue of their age, but rather according to whether they had yet learned to walk (onset of walking ability varied across the group, but all were walking by 15 months).

Irrespective of age, Clearfield found that infants gestured far more during their first walk session compared with their last crawl session, and that they interacted with their mothers more, and their toys less, during their first walk session compared with both their last crawl session and their second walk session.

By twelve months of age, eight members of this final infant group were walking, whilst six were still crawling. Comparing the walkers and crawlers revealed once again that the walkers interacted more with their mothers and performed more social gestures. 'This more mature mode of interaction did not come about through age or more experience in the world,' Clearfield said, 'but rather, the transition to independent walking itself changed how infants interact with others.'

The message is that the same developmental processes that lead an infant to take its first steps, also seem to drive changes in their social behaviour. Importantly, the baby walker study showed this isn't simply because of different opportunities afforded by being in an upright position. 'Under this explanation,' Clearfield concluded, 'processes such as perception, attention, memory, cognition, and social behaviours all shift to accommodate infants' new mode of moving through the world, and each process affects and is affected by the changes in the other processes. From this dynamic view, learning to walk becomes much more than simply a motor milestone; instead, it becomes the core of system-wide changes across many developing domains.'
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2 comments:

I'm wondering: which comes first, the ability to walk, or the cognitive change? It seems the ability to walk is a result of the cognitive change (as being in an upright walking position via the baby walker does not yield cognitive change). But is this enough proof?

This is a really nice example of how one key change in development can open the door to a whole array of new behaviours.

But I have a few caveats:

Firstly, a walking infant has hands free to make gestures more easily and the head is at an angle that makes eye contact much easier. Crawling babies do make gestures and eye-contact, but offering an object to another person and looking at their face while you do it, requires an awkward tripod stance, roll of the shoulder and twist of the head that aren’t required when upright.

Secondly, I would question the distinction between ‘motor’ and ‘social’. There is a distinction, from the observer’s point of view, but not necessarily from that of the brain of the infant. An upright posture facilitates motor behaviours - direction of gaze, hand gestures - that crawling doesn’t. I think we need to be careful not to impose an essentially arbitrary behavioural classification system that divides behaviours into motor, cognitive, social etc. on the emergent, dynamic outcomes of developmental processes.

Third, it might be worth noting that many children with developmental abnormalities, including autism, often omit the crawling stage. But walking, for autistic children, does not appear to facilitate social interaction and gesturing. Indeed, occupational therapists often see the omission of crawling as causing developmental problems.